Flat Frequency
All home stereo speakers are designed (ultimately)
to have the "flattest" possible frequency response. Flat (in this context)
does not mean being off pitch but means linear, like a line drawn with a
ruler --- all parts of the frequency spectrum (bass, midrange, and treble)
get equal weighting of the sound. Every recording studio in the world has
(ultimately) a flat pair of speakers to monitor their recordings on. That
way, every album mix should have roughly the same balance of bass and treble.
Look at your album (or movie) credits (they so often go unnoticed). Parts of
a song may be recorded at one studio and the vocals elsewhere.
The final mix may be at an entirely different location (maybe in a different
country) and then there is the mastering. If you have a compilation album of
different artists (probably bought on one of those TV ads) there may even be
a final mastering to get all of the tunes to sound cohesive (in frequency
response and volume level). All of these studios need a reference (square
one) where they can find the scheme of the "big picture" --- this
is a flat frequency response.

Drivers
Speaker design engineers are paid to produce a line
of speakers that are flat in response over the frequency range. This is not a
process of putting a few speaker components, or drivers, in a pretty
box, but of designing the box to complement the ultimate driver(s) for the frequency
range. Please read our page on the importance of box tuning.
Woofers (the big, low frequency drivers) depend on the cubic footage and
"stiffness" of air inside the box to produce their sound while most
midrange drivers (and all tweeters) are independent of the box and require
different techniques to match the other drivers and produce good sound.

CrossoversCrossovers are the electrical components hidden
inside each speaker cabinet that divide and route the bass, midrange and
treble signals to the appropriate drivers. Crossovers are really the heart of
the speaker and crossover design separates the "men
from the boys" in the speaker world. Although some retail stores
sell things that they call "crossover networks" to the "build
your own" crowd, these are shunned much as an
"off the rack" suit or dress would be shunned by the fashion
conscious. Boy, I could write another page (of this one's length) just on the
hows and whys of crossover design (but thats not why we're here). Let's
just say that, for great sound, each crossover must be "tailored"
to its application.

Unless you bought your
speakers second hand, you probably went to the stereo store and listened (or
A/B tested) many different brands of speakers and picked the one that sounded
the best to you. Granted, not everyone has a perfectly "flat" ear, you picked the pair that sounded best to your ear
(probably on your favorite album).

The question that I pose is --- now that your
speakers need repair, why would you consider second-guessing the engineer of
your speaker by replacing the damaged drivers with substandard components?